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Granite is a widely occurring type
of igneous stone. Igneous means it
is formed from magma, which is a hot, fluid
rock beneath the surface of the earth. Granites
are usually medium to coarsely crystalline.
Granites can be pink to dark gray or even black,
depending on their chemistry and mineralogy.
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The granite
peaks called the
Towers of Paine in Chile. |
Granite has many potential origins within
the earth's crust, but to be granite it must intrude
other rocks. This means that under pressure molten
magma must be forced into other rocks. The actual
process that produces granite in the earth's crust
is disputed and has led to varied schemes of classification.
Granite formations are nearly always massive
(meaning they lack internal structures), hard
and tough. As a result granite has gained
widespread use as a construction stone.
The word granite comes from the Latin word
"granum," meaning a grain. This is because
of its coarse-grained crystalline structure.
Historical Uses of Granite
The Red Pyramid of Egypt, the third largest
Egyptian pyramid, is named for the light crimson
hue of its exposed granite surfaces. The Great
Pyramid of Giza contains a huge granite sarcophagus
fashioned of "Red Aswan Granite." Because
of its durability and beauty, ancient Egyptians
also used granite in high wear areas of buildings
such as to make columns, door lintels, sills,
jambs, and as wall and floor veneer.
Many large Hindu temples in southern India,
particularly those built by the 11th century
king Rajaraja Chola I, were made of granite.
There is a large amount of granite in these
structures and they are comparable to the
Great Pyramid of Giza.
An unusual use of granite was for the construction
of the rails for the Haytor
Granite Tramway, in 1820 in Devon, England.
Modern Uses Of Granite Granite
has been extensively used as a dimension stone
and as flooring tiles in public and commercial
buildings and monuments. With increasing amounts
of acid rain, granite has begun to supplant
marble as a monument material, since it is
more durable. Polished granite is also a popular
choice for kitchen
countertops due to its high durability
and aesthetic qualities.
Granite is currently known only to exist where it forms a major part of continental
crust. Granite often occurs as relatively
small, less than 100 km sq. stock masses and
in batholiths that are often associated with
orogenic mountain ranges.
Granitic rock is widely distributed throughout
the continental crust of the Earth and is
the most abundant basement rock that underlies
the relatively thin sedimentary veneer of
the continents. However, since granite formations
may exist as deeply as 150 miles, it is only
asccessible for quarrying in limited locations.
The countries with the most commercial granite
include Finland, Norway and Sweden, Spain,
Brazil, India and several countries in southern
Africa, such as Angola, Namibia, Zimbabwe
and South Africa.
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